Dynamic control of code modulated pulse transmission

(54) Designation: Dynamic control in code modulating pulse transmission systems

1st Field of the Invention

The invention relates to a signal transmission transmission system by pulse code modulation wherein the transmitter is provided with a device for dynamic compression and the receiver with a device for dynamic expansion, each having a dynamic control circuit in which a pulse train analyzer is arranged, which analyzes a transmitted pulse train and then emits a pulse train. pulse patterns occur which, within a fixed and limited time interval of at least three successive pulses, corresponds to a large instantaneous modulation index, said dynamic control circuit further having a signal generator which emits a dynamic control signal under control through the output pulses of said pulse train analyzer, which dynamic control signal is derived from an integrating network arranged in the signal generating tower and modulates the transmitted pulse train.

2nd Prior art

A transmission system as described above is known from Dutch patent application 6803992. In this known plant, the signal generator may be equipped with an amplifier connected to the integrating network, which amplifier has an exponential amplification characteristic so as to be able to accurately follow the rapid variations of the various variations according to the present invention. ,, to be transmitted. In another name

7608186-8 arrangement, for example, as described in Dutch patent application 7311912, the integrating network is designed as a non-linear circuit with a diode, whereby the time constant of the integrating network depends on the level of the dynamic control signal. As the pulse train analyzer emits a series of output pulses in these known systems, an exponentially increasing dynamic control signal is obtained through the use of non-linear elements, which has the disadvantage that it is difficult to achieve reproducibility, so it is almost impossible to realize similarity between the exponential dynamics. the regulation of transmitters and receivers.

3rd Brief description of the invention

An object of the invention is to provide another embodiment of a transmission system as above, where an exponential variation in the dynamic control signal is obtained without the use of non-linear elements such as diodes or amplifiers having an exponential amplification characteristic.

The transmission system according to the invention is therefore characterized in that said signal generator further comprises a feedback circuit which is coupled between an output and an input of said integrating network and comprises a first device coupled to said output on the integrating network for providing a signal. , which has a relation in relation to said dynamic control signal in accordance with a selected ratio, and a second device coupled to said pulse train analyzer, said first device and said input on the integrating network for supplying said signal provided by the first device to said integrating network in dependence on said output pulses.

In applying the measures according to the invention, it is further achieved that a wider scope of application of the described plant becomes possible, since said ratio can be selected in a simple manner and the signal generator can furthermore be fully designed with digital elements.

4th Summary of the figures

The invention is explained with reference to the drawings, in which Fig. 1 shows a transmission system according to the invention, Fig. 2 shows a signal generator for use in the transmission system according to Fig. 1, Fig. 3 and Fig. 4 shows embodiments of the signal generator according to Fig. 2, and Fig. 5 »Fig. 6 shows additional signal generators which are particularly suitable for digital technology execution.

5th Figure Description

The transmission system according to the invention, shown in Fig. 1, is designed for transmitting information signals encoded by delta modulation but also other forms of pulse code modulation, such as, for example, delta signal modulation can be used.

In the transmitter shown in Fig. 1a, signals to be transmitted via a receiving device 1 to a screen reader 2, to which also a reference signal is supplied via a reference circuit 3 provided with a local receiver 4 having a decoding circuit 5, which in Fig. 1a is shown as a integrating networks. Due to the polarity of the output voltage of the disk generator 2, pulses derived from a pulse generator 6 are generated at the output of a sampling device 7 or the pulses are suppressed. A pulse generator 8, which is controlled by the pulse generator 6, is connected in known manner to the output of the sampling device 7. The regenerated pulses are supplied to the local receiver 4 and can also be transmitted to an associated receiver via the conductor 9 · The local receiver 4 has a pulse train analyzer 10, which analyzes the pulse train to be transmitted and which, during the occurrence of pulse patterns which, within a fixed and limited time interval of at least three successive pulses in the pulse generator 6, correspond to a large instantaneous modulation index, emit output pulses which are fed to an input terminal 11 of a signal generator 12. From the output pulses of the pulse train analyzer 19, the signal generator 12 forms a dynamic control signal generated at the output terminal 13 and with which the energy content of the pulses to be transmitted is modulated in a pulse modulator 14. These modulated pulses are applied to the decoding circuit 5 to generate the reference signal.

Fig. 1b shows a receiver designed to cooperate with the transmitter of Fig. 1a in a transmission facility according to the invention. The elements having equivalents in Fig. 1a have been given the same reference numerals in Fig. 1b. The transmitted pulses are received via the conductor 9 and fed to a pulse generator 8, which is controlled by a pulse generator 6. The pulse generator 6 in the receiver can be synchronized in known manner. with the pulse generator 6 in the transmitter.

As in the local receiver 4 of the transmitter shown in FIG. 1, also in the receiver according to FIG. 1b, by the signal generator 12, a dynamic control signal is generated by the pulses fed by the pulse train analyzer 10 to the input terminal 11, which control signal is derived from the output terminal 13 and with which the transmitted pulse train is transmitted. modulated in the pulse modulator 14; The modulated pulse train is converted by the decoding circuit 5 into a signal corresponding to the reference signal in the transmitter and then fed to a display device 20. In order to obtain an exponential variation of the dynamic control signal, the signal generator 12 according to the invention is provided with a feedback circuit 15, which in the embodiment according to FIG. 1 consists of an amplifier 16 and a summing device 17. The dynamic control signal derived from an integrator 18 is applied to an input of the amplifier 16. The summing device 17 adds a signal of low value to the signal emitted by the amplifier 16, after which the resulting signal in a pulse modulator 19

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modulates the output pulses of the pulse train analyzer 10, which occur at the input terminal 11 of the signal generator 12. The modulated pulses are applied to an input of the integrator 18 to build up the dynamic control signal.

In order to limit the increase in the dynamic control signal at large values, the pulse modulator 19 must also be provided with a limiter in such a way that only a given maximum signal value is supplied to the integrator 18.

The signal generator 12 of Figure 2 corresponds substantially to the signal generator 12 of Figure 1. Elements corresponding to Figure 1 have been given the same reference numerals as in this figure. In the signal generator 12 of Fig. 2, the summing device 17 is connected between an output of the pulse modulator 19 and an input of the integrator 18. The voltage supplied via a damping device 21 by the summing device 17 is derived from the output pulses of the pulse train analyzer, which output pulses appear on the input terminal 11.

Fig. 3 shows an embodiment of a signal generator intended for use in a transmission system according to the invention. Transistors 22 and 23 form a pulse amplitude modulator designed to modulate the output pulses of the pulse train analyzer, which occurs on the input terminal 11, with the signal supplied via the feedback circuit 15. The pulse amplitude modulator inputs comprise the bases 2b and 25.

The carbon lectors 26 and 27 are connected to a negative voltage of 4.5 V. The input to the integrator, which consists of transistor 28, capacitor 29 and resistors 30, 31 and 32, is formed by node 33 of emitter 34, base 35 and resistors 36 and 37 · The resistor 37, which connects the emitter 38 of the transistor 23 to the node., 33, determines the minimum amplitude of the integrator pulses. The dynamic control signal supplied to the output terminal 13 is derived from the capacitor 29 and is also fed to an input of the pulse amplitude modulator via the amplifier 16 of the feedback circuit 15.

Fig. 4 shows another embodiment of a signal generator where the pulse amplitude modulator is made up of transistors 39, 40 and 41. Amplifier 16 mentioned in the description of Fig. 1 consists of resistors 42 and 43, whose common point 44 is connected to the base 45 of transistor 40. The input to the integrator, which consists of resistors 32, 42 and 43 and capacitor 29, is the emitter 46 of transistor 41. The diode 47, which is connected between the node 48 of the resistor 49 and the transistor 40's carbon diode 50, prevents the voltage on the integrator from dissipating via the parasitic capacitance between the base 45 and the colector 50 when the switch 51> operated by the pulses acting on the input terminal 11, su1 thesis.

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To compensate for the transient voltage of diode 47, another transistor 53 is connected between node 48 and base 52 of transistor 41. Resistor 37. which connects emitter 54 of transistor 40 to node 55 of emitter 56 and current source 57 determines the minimum amplitude of the integrator pulses. The transistors 39, 41 and 53 of the transistors 39, 41 and 53 respectively are connected to a positive voltage as is the resistor 49. The dynamic control signal appearing on the output terminal 13 is derived from the capacitor 29 and is also supplied via the feedback circuit 15 to the base 61 which forms an input to the pulse amplitude modulator.

Fig. 5 shows an example of a signal generator made in digital technology. Here, the pulses appearing on the input terminal 11 control a switching device 62 in such a way that a code word appearing on an input 63 is only fed to a summing device 64 when said pulses are present. The code word appearing at the input 63 is formed by the summing device 17 of the sum a code word representing a constant value, and a code word having a ratio determined by the multiplier 65 to the code word appearing at point 66, which is later code word represents the dynamic control signal. The combination of the summing device 64, the delay network 67 and the multiplier 68 forms a digital version of the integrator 18 shown in Fig. 1.

Fig. 6 shows another example of a signal generator made in digital technology and intended for use in a transmission system according to the invention.

In this embodiment, it has been assumed that the pulse signal appearing on the input terminal 11 consists of non-return-to-zero pulses, in other words, that the duration of a logical zero is equal to the duration of a logical one. The dynamic control signal appearing on the output terminal 13 is represented by a code word emitted by an accumulator 69. Via the feedback circuit 15 and the switching device 62, this code word is processed in the same manner as described with reference to Fig. 5. In the embodiment of Fig. 6, a second switching device 70 is controlled via an inverting input 71 on the second switching device 70 by the pulses occurring on the input terminal 11. This second switching device conducts the code word appearing on the output of accumulator 69 after being weighted in a multiplier 68 to the summing device 64 in the absence of pulses on the input terminal 11. In this embodiment, the integral network 18 shown in Fig. 1 is constituted by the combination of the summing device 64, the accumulator 69, the multiplier 68, and the controller 70.

It is observed that the oblique lines in the connections between the elements of Figures 5 and 6 indicate that a serial or parallel transmission of pulses takes place along these connections.

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6th Mathematical description of the embodiments shown

At times determined by the pulse generator 6 of Figure 1, the dynamic control signal appearing on the output terminal 13 may be represented by:

^sk ^ΡΛ-1 * ⁸> * “At ..........¹

Hereby are:

= the size of the dynamic control signal at time t = kT

P = 1 if the pulse train analyzer 10 emits a pulse at time t = kT

P_R = 0, if the pulse train analyzer 10 does not emit a pulse at time t = kT

A, B and C are constants determined by the values ​​of the elements of the signal generator 12. k = an integer

T = the time between two successive pulses in the pulse generator 6

For the signal generators shown in Figures 1 and 2 are:

A = b (i-exp (-T / Γ,))

B = the voltage V supplied by the summing device 17 C = exp (-T / £ p where:

b = amplifier 16 gain factor = charging time constant for integrator 18

- £> 2 = discharge time constant for integrator 18 For = 1 now applies:

S_k = (b (l-exp (-T / rp) + exp (-T / ^)) S_k_₁ + V and for P, = 0 k ^sk = ^sk_i-exp (- · ^)

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In the signal generators of Figures 5 and 6, constants A, 8 and C are given by:

B = o <

^{C = Y}k so that for P. = 1: k ^sk ^Xk^sk-1 - ^Sk-1 ^{+ (x}k - ^{l) s}at and before

<img file="SE409794B_D0001.tif" />

^{= S}k-1 ⁺ (Y.

Ds k-1

On the basis of the given mathematical description of the function of the signal generators, it is obvious that other constructions are conceivable, which utilize the most important features of the invention, namely the feedback circuit, the amplifier and the switching device, which are characterized by

A and R 2, respectively.

An important advantage of the invention is that the ratio, i.e. the constant A, by which the output signal of the amplifier or multiplier is related to the output of the integrating network, can be set in a simple manner and that the setting can be obtained, for example, by switching on another amplifier or multiplier or by affect the condition itself when a predetermined sequence of pulses occurs in the pulse train analyzer.

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